Move SpeechManager from sugar to sugar-toolkit-gtk3

This is done to be able to use this implementation of the feature
in the activities. A complementary patch is needed in sugar module.
Add a list of language names to translate

To display a list of translated language names in the UI,
we add a list of the available languages, because the espeak
language names are not translated.
TTS: Cache the voices list
Initialize Gst before use speech

In sugar gst was initialized at startup, now we need initialize Gst
in the speech code.
Add a structure to store the translated voice names
Add parameters to configure tts

Activities can set pitch, rate or voice used to play text to speech